Control arrangement for pneumatic hammers

ABSTRACT

A control arrangement for pneumatic hammers comprises a reciprocating rocking piston for actuating an impact cutter and a rocking slide for controlling the input of the compressed air and the output of the consumed air. After a predetermined control angle of the rocking slide a tension means effects a complete reversal of the rocking slide and the rocking piston.

United States Patent Balve [451 May 23, 1972 1 CONTROL ARRANGEMENT FOR 575,970 1/1897 McCulloch .;....91/29o PNEUMATIC HAMMERS 2,906,245 9/1959 McCall ..91/29o 3 166 988 1/1965 Kohler ..9l/347 1 [72] Invemr' fflzg gfi g me St Remlch 3,296,938 1/1967 l-Iayman ..91/347 Ffled: 1969 Primary ExaminerPaui E. Maslousky [21] Appl 3 794 Attorney-John J. Dennemeyer [30] Foreign Application Priority Data [57] ABS CT Jan 23 1969 Luxembour 57 835 A control arrangement for pneumatic hammers comprises a g reciprocating rocking piston for actuating an impact cutter 52 us. Cl ..91/290, 91/347 and a mkmg slide "l the input P' I 5 1 1 air and the output of the consumed air. After a predetermined [58] Field of Search ..91/290, 347 Control gle of the rocking slide a tension means efiects a complete reversal of the rocking slide and the rocking piston. [56] References Cited UNITED STATES PATENTS 495,l26 4/1893 Duzee ....9l/290 4Clalns,5DrawlngHgures i ii.

CONTROL ARRANGEMENT FOR PNEUMATIC HAMMERS The invention relates to a control arrangement for pneumatic hammers and more particularly for pneumatic compacting and cutting hammers having a control valve for conducting a pressure fluid to an upper and a lower cylinder chamber of a piston which reciprocates in a cylinder.

It is an object of the invention to provide a new and improved control arrangement for feeding and discharging the pressure medium to and from the chambers.

According to the invention this is obtained in that in a rocking slide two arcuate-shaped control cavities that extend parallel in adjacent axial relationship are provided so that one control cavity feeds the input of compressed air from a compressed air inlet chamber disposed in the cylinderhead alternately into the upper or lower cylinder chamber while the second control cavity leads the consumed compressed air from the upper as well as the lower cylinder chamber to the outside wherein the actuation of the rocking slide for its required reversing movement is initiated by means of a rocking piston, which is mounted centrally axially in front of the rocking slide with a claw coupling at a predetermined lead angle, and that the rocking piston is moved ahead by the compressed air in the upper and lower cylinder chamber by opening the respective compressed air inlet canals by means of the upper and lower edge of the impact piston, and wherein the rocking piston puts a draw or compression spring under tension which produces automatically after a predetermined control angle due to its tension force the complete reversing of the rocking slide and of the rocking piston up to the required stop in both operating directions.

According to a preferred embodiment of the invention an adapter segment is fixed in a cylindrical through-bore of the cylinder head, wherein the rocking slide as well as the rocking piston are mounted centrally and axially in sequence, in the axial artial section of the rocking piston, and are provided with a hard carbon sealing strip towards the rocking piston shaft, and the rocking piston may also be provided with an axially extending hard carbon sealing strip.

An embodiment of the invention is illustrated in the accompanying drawing and will be described in greater detail hereafter.

In the drawing:

FIG. 1 is a section through the rocking slide in the cylinder head of the cylinder,

FIG. 2 is a section through the rocking piston which is also arranged in the cylinder head and is disposed centrally axially behind the rocking slide, wherein also the compressed air inlet canals to the rocking piston are shown,

FIG. 3 is an enlarged view of the rocking piston with the associated control angles,

FIG. 4 is a view of the draw spring which produces the complete reversal of the rocking slide.

FIG. 5 is a section along the cylindrical through-bore of the cylinder head with a three dimensional view of the elements within the through-bore, namely the rocking piston and rocking slide (shown disengaged from each other) and the claw coupling having two coupling halves, one on the rocking piston shaft, the other on the rocking slide to couple these elements together.

Referring now to the drawing it will be seen that in FIGS. 1 and 4 the rocking slide 1 is maintained in the stop position by the draw spring 25 over a tension lever 26 and by the rocking piston shaft 29 and its claw coupling 30. The control cavity 3 of the rocking slide 1 connects the compressed air inlet canal 8 of the compressed air inlet chamber 9 with the compressed 7 air inlet canal 4 to the upper cylinder chamber 10 wherein the incoming compressed air accelerates the impact piston 11 which strikes the impact cutter 15.

Simultaneously the rocking slide 1 keeps the air outlet canal 5 closed towards the outlet canal 7 while it connects with its second control cavity 2 the alternating flow canal 6 to the outlet canal 7 and the consumed compressed air of the lower cylinder chamber 14 flows during the entire downward stroke (impact stroke) to the outside. During the upward stroke shortly before the impact on the impact cutter 15 the upper edge 12 of the impact piston opensthe compressed air inlet canal 20 to the rocking piston 21 (FIG. 2), wherein the compressed air flows into the pressure chamber 22 between the stationary segment 24 and the rocking piston 21 (FIGS. 2 and 3). Accordingly the rocking piston 21 is movedahead by a predetermined angle A B wherein simultaneously the draw spring 25 is tensioned up to the perpendicular 0 point (FIGS. 3 and 4). The rocking piston is moved further by means of the compressed air and as soon as the suspension point 32 of the draw spring 25 rotates the 0 point over to B the rocking slide is reversed from B to C by means of the claw 30 fixed thereon.

In this manner it is obtained first that the rocking piston 21 abuts against the rocking slide 1 and rotates it still further by a predetermined angle, and secondly due to the suddenly operating draw force of the draw spring 25 the rocking slide 1 is reversed at B completely up to the stop, wherein the rocking piston 21 will be located exactly at point C. At the same time the outlet canal 5 of the upper cylinder chamber 10 was connected through the control cavity 2 of the rocking slide 1 with the outlet canal 7 so that the consumed compressed air is discharged to the outside and simultaneously the connection between the alternating flow canal 6 and the outlet canal 7 is closed. The control cavity 3 of the rocking slide 1 makes simultaneously the connection between the compressed air pressure chamber 9 over the canal 8 and the alternating flow canal 6 so that the compressed air flows into the lower cylinder chamber 14 and guides the impact piston 11 again upwardly. As soon as the lower edge 13 of the impact piston opens during the upward stroke (reverse stroke) the compressed air inlet canal 19 to the rocking piston 21, which by the previously executed reversing process now maintains the rocking slide 1 in abutment at point C the compressed air flows over the inlet canal 19 to the pressure chamber 23 on the left side of the rocking piston 21 which is moved ahead from point C to D (FIGS. 3 and 4) wherein the compressed air guides the impact piston 11 further upward, and the upper edge 12 of the impact piston moves past the outlet canal 5 (FIG. 1) and compresses the remaining air (air cushion) left in the upper cylinder chamber 10, while in the meantime the rocking piston 21 tensions the draw spring 25 and has pushed its suspension point 32 already beyond point D (FIGS. 3 and 4). During this operation the draw spring 25 has reversed the rocking slide 1 back into the starting point A completely to the stop position and maintains the rocking slide 1 at the stop position. The impact stroke of the impact piston 1 l on the impact cutter 15 is thus initiated, and the cycle is repeated in the sequence described. In order to prevent a leaking of the compressed air hard carbon sealing strips 27 and 28 are provided on one side between the segment 24 and the shaft 29 and on the other side between the rocking piston 21 and the bore in the cylinder head. Due to the cast arrangement of all the air inlet and outlet canals and the control canals for guiding the rocking slide 1 and the impact piston according to the invention substantial machining costs relative to the complicated travel of the canals and thus a less expensive manufacture of the entire pneumatic hammer may be obtained.

What is claimed is:

l. A control arrangement for pneumatic hammers having a cylinder with a cylinder head, a reciprocating piston movable within the cylinder and defining an upper and a lower cylinder chamber, the control arrangement comprising:

a rocking valve disposed in the cylinder head to control the flow of pressurized fluid through inlet and outlet channels toward and from the cylinder chambers, the oscillating valve having two parallel, axially adjacent, arcuateshaped control cavities, one control cavity controlling the input of compressed air from a compressed air inlet chamber arranged in the cylinder head alternately into the upper Or lower cylinder chamber while the other cavity vents the consumed compressed air alternately from the lower or upper cylinder chamber to the outside;

a rocking piston to actuate the rocking valve for its required reversing movement, the rocking piston being axially aligned with the rocking valve and being connected thereto by means of a claw coupling, whereby one side of the rocking piston is connected by a control passage to one of the cylinder chambers, and the other side of the rocking piston is connected by a further control passage to the other cylinder chamber, and whereby the control passages are opened and closed alternately by the upper edge and lower edge of the reciprocating piston so as to move the rocking piston and control the reversing movement of the valve by means of the compressed fluid in the upper and lower cylinder chambers; and

a tension spring connected between the rocking piston and I the cylinder head to effect, after a predetermined movement of the rocking piston, automatically the complete reversal of the rocking valve in both directions.

2. A control arrangement according to claim 1, wherein a cylindrical through-bore is provided in the cylinder head, the through-bore receiving the rocking valve and the rocking piston, and wherein an adapter segment is fixed in the through-bore and defines together with the rocking piston two cylinder chambers to which the control passages are connected.

3. A control arrangement according to claim 2 wherein a sealing element is disposed between the adapter segment and the rocking piston and a further sealing element is disposed between the rocking piston and the through-bore, and whereby the sealing elements are hard carbon sealing strips.

4. A control arrangement according to claim 1 including a cast arrangement of the inlet and outlet channels and the control passages in the cylinder head. 

1. A control arrangement for pneumatic hammers having a cylinder with a cylinder head, a reciprocating piston movable within the cylinder and defining an upper and a lower cylinder chamber, the control arrangement comprising: a rocking valve disposed in the cylinder head to control the flow of pressurized fluid through inlet and outlet channels toward and from the cylinder chambers, the oscillating valve having two parallel, axially adjacent, arcuate-shaped control cavities, one control cavity controlling the input of compressed air from a compressed air inlet chamber arranged in the cylinder head alternately into the upper or lower cylinder chamber while the other cavity vents the consumed compressed air alternately from the lower or upper cylinder chamber to the outside; a rocking piston to actuate the rocking valve for its required reversing movement, the rocking piston being axially aligned with the rocking valve and being connected thereto by means of a claw coupling, whereby one side of the rocking piston is connected by a control passage to one of the cylinder chambers, and the other side of the rocking piston is connected by a further control passage to the other cylinder chamber, and whereby the control passages are opened and closed alternately by the upper edge and lower edge of the reciprocating piston so as to move the rocking piston and control the reversing movement of the valve by means of the compressed fluid in the upper and lower cylinder chambers; and a tension spring connected between the rocking piston and the cylinder head to effect, after a predetermined movement of the rocking piston, automatically the complete reversal of the rocking valve in both directions.
 2. A control arrangement according to claim 1, wherein a cylindrical through-bore is provided in the cylinder head, the through-bore receiving the rocking valve and the rocking piston, and wherein an adapter segment is fixed in the through-bore and defines together with the rocking piston two cylinder chambers to which the control passages are connected.
 3. A control arrangement according to claim 2 wherein a sealing element is disposed between the adapter segment and the rocking piston and a further sealing element is disposed between the rocking piston and the through-bore, and whereby the sealing elements are hard carbon sealing strips.
 4. A control arrangement according to claim 1 including a cast arrangement of the inlet and outlet channels and the control passages in the cylinder head. 